package com.atguigu.singleton.type3;


public class SingletonTest03 {
	public static void main(String[] args) {
		//测试
		System.out.println("懒汉式，线程不安全~");
		Singleton instance = Singleton.getInstance();
		Singleton instance2 = Singleton.getInstance();
		System.out.println(instance==instance2);//true
		System.out.println("instance.hashCode="+instance.hashCode());
		System.out.println("instance2.hashCode="+instance2.hashCode());
	}
}


class Singleton{
	private static Singleton instance;
	
	private Singleton() {
	}
	
	//提供一个静态的公有方法，当使用到该方法时，才去创建instance
	//即懒汉式
	public static Singleton getInstance() {
		if(instance == null) {
			instance = new Singleton();
		}
		return instance;
	}
}